Doors open at 6:30pm, and an astronomer will present a half-hour public talk, starting at 7.15pm. This is followed by an opportunity to look through the historical Northumberland and Thorrowgood telescopes if the weather is clear. Members of the Cambridge Astronomical Association also set up modern telescopes on the observatory lawns, with video projection facilities and expert commentary. We can't always guarantee observing, of course, as it is very weather-dependent. On a cloudy evening, the talk will instead be followed by tea and biscuits, and some short entertainment from the CAA.

Seating in the lecture theatre is available on a first-come, first-seated basis - if it's full, we'll do our best to seat you in an overspill room, where the talk will be live-streamed. We are also hoping to stream our public talks live to the web next season, and also archive the recordings.

If you wish to skip the talk and only attend the observing, please arrive at 7.45pm (don't arrive before this, as we'll be still setting up!).

Families recommends that you always check details of the event with the organiser.